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"Kaido Kert" wrote in message om... "Christian Ramos" wrote in message ... There appears little room for payload now, so placing biologicals and associated life support on those payloads seems a bit ridiculous, I asked the same question in another online discussion, and got the number of around 50kg for one rat and its consumables for a six-month cruise, including associated equipment. I suspect its closer to 100 but still not prohibitely high. Hmm. I think that would be significant unless it was on its own mission. let alone the fact that you would have to go to mars to actually retreive the rats.. Additionally, rats arent really going to cut it in determining the effect on humans, plants and other species. Its not absolutely necessary to retrieve them, is it ? We could simply pack sufficient health monitoring equipment along. Of course, returning it back to earth and monitoring the long-term effects would be even better, so if you have a mars sample return mission, it would be perhaps possible to return biological experiments from martian orbit along with surface sample. I'm not aware of such equipment, you would probably have more luck utilising cell cultures and such, but again the data would only marginally be relevant. We're not talking about radiation as comes out of reactor core, it is a different thing. Obivously effects on humans would be far from certain with rat experiment, but we could be a lot more confident, after all we have used rats for such purposes for centuries. But packing a couple plants along would be a good idea of course, especially because those wouldnt cost much in a payload. We're probably, getting into the realms of where experts in the area need to comment, however, the documents I've read indicate this wouldnt be viable. It's more than monitoring their health, you want to see what damage is down for both different fluxes of radiation and accumulated forms of radiation. How would you match them. You could probably measure the radiation, a sophisticated thing when talking space operation, but how would you measure the impact on cells for each form, how would you determine the secondary effects and interations between various forms of damage and other biological processes, how would you differenatiate changes from radiation as opposed to gravity or environmental. Eventually some living organism is going to have to take the trip, and it would be kinda stupid to have the first human crew as test subjects. Why..I dont remember Nasa sending rats to the moon before the Apollo landing. But they put chimps in Mercury capsules, didnt they. US was in a race then and didnt have enough time to do it. Were there never plans to put animals on Surveyors ? Sure..But the Mercury capsules were LEO that is not that environment of outer space that the apollos encountered on the way to the moon. As for the data that was gathered, well I would guess it gave them a systems integration perspective, ie: does everything seem to work. Space was very much an unknown which probably drove the chimps and dogs in space, although, it's an interesting question, why did the chimp go into to space, was it just a conservative approach to validation or something else. I'm sure in one of the historical books I've read that the chimp decision was made by Von braun given his lack of confidence in the boosters, but I could be totally screwed up there, will have to dig them up once my "lab" is complete |
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On Thu, 11 Nov 2004 00:02:36 GMT, Christian Ramos
wrote: VASIMR, seems to me like a technology toy looking for a real life solution. How would you envisage VASIMR being used. Although, given a space based research program that furthers our understanding into magnetics and plasmas things could change, but the benefits are more likely to flow through to technologies such as the Russian MPD thrusters. I've looked over MPD and it seems like it produces far lesser thrust per wight of gas. I might be wrong.. The idea of VASIMR is to get variable thrust of significant % of g force and be able to maintain it over a long time. Getting the energy from a reactor greatly reduces the amount of propellant needed. As I've said a nuclear fission produces approx 1 000 000 times the amount of energy you would get from a chemical reaction. (Not that you can utilize all of it..) I see it used for manned interplanetary flight. Particularly continous acceleration means that the peaple are exposed to cosmic radiation and zero g for much lesser periods of time. For unmanned flight a ion engine might be a alternative. (DeepSpace1 et.al) -- Using M2, Opera's revolutionary e-mail client: http://www.opera.com/m2/ |
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"John Thingstad" wrote in message news On Thu, 11 Nov 2004 00:02:36 GMT, Christian Ramos wrote: VASIMR, seems to me like a technology toy looking for a real life solution. How would you envisage VASIMR being used. Although, given a space based research program that furthers our understanding into magnetics and plasmas things could change, but the benefits are more likely to flow through to technologies such as the Russian MPD thrusters. I've looked over MPD and it seems like it produces far lesser thrust per wight of gas. I might be wrong. It may, although it would be interesting to compare end to end conversion of the energy to thrust output. MPD is also on my list of a propulsion system that I "should" be able to build at "home", VASIMR on the other hand is not. My thinking was along the lines that further research into plasma dynamics and magnetic fields is going to have more direct bearing to MPD first and then vasmir later. That is, their is much more room for performance improvement on the MPD side which may then flow through to things such as VASIMR. .. The idea of VASIMR is to get variable thrust of significant % of g force and be able to maintain it over a long time. Getting the energy from a reactor greatly reduces the amount of propellant needed. As I've said a nuclear fission produces approx 1 000 000 times the amount of energy you would get from a chemical reaction. (Not that you can utilize all of it..) Well the question I would ask is, if you have a reactor on board your craft, would you not be better to pump the fuel directly through the reactor rather than convert to electricity then convert back to heat the propellant. This is a numbers question though, have you ever compared? Also, given our limited understanding of plasma and magentic sciences, are we even sure that such a device would work well in "Outer Space" with all kinds of external plasma and magnetic interactions This later is a question I've never seen addressed so perhaps I'm being paranoid. I see it used for manned interplanetary flight. Particularly continous acceleration means that the peaple are exposed to cosmic radiation and zero g for much lesser periods of time. I always have a problem with these types of solutions of long term acceleration. Once you get to such speeds that make Interplantary travel viable, arent you also going to be at a speed where even the impact of dust particles could devastate your ship. Your ability to maneuver is also compromised with such a solution. |
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On Sat, 13 Nov 2004 02:20:38 GMT, Christian Ramos
wrote: . The idea of VASIMR is to get variable thrust of significant % of g force and be able to maintain it over a long time. Getting the energy from a reactor greatly reduces the amount of propellant needed. As I've said a nuclear fission produces approx 1 000 000 times the amount of energy you would get from a chemical reaction. (Not that you can utilize all of it..) Well the question I would ask is, if you have a reactor on board your craft, would you not be better to pump the fuel directly through the reactor rather than convert to electricity then convert back to heat the propellant. This is a numbers question though, have you ever compared? Well utilizing the heat from the reactor directly is certainly easier. It was the first idea and explored already back in the 50's. Of course then it was though to be used in the atmosphere something we would never consider today. But a atomic reactor can generate electricity with good efficiency. (Except the RORSAT reactor (Russian..) mentioned elsewhere) Heating has directly you could not possibly put as much energy into the gas. Then there is the fact that the gas flow would have to be high to have a cooling effect. P = m*v and we want m as small as possible and v as large as possible. (I am talking about the propellant not the ship per se though the same applies here.) Seems to me magnetic induction of ions wins hands down. Also, given our limited understanding of plasma and magentic sciences, are we even sure that such a device would work well in "Outer Space" with all kinds of external plasma and magnetic interactions This later is a question I've never seen addressed so perhaps I'm being paranoid. Knowledge of magnetic's is (or really electro-magnetics) is decidedly where our science is the most advanced. Plasma flow seems sufficiently well understood to make a working motor. (Not that you should be asking me about this.. http://www.ae.utexas.edu/design/phoenix/vasimr.html and references should give you an idea.) I see it used for manned interplanetary flight. Particularly continous acceleration means that the peaple are exposed to cosmic radiation and zero g for much lesser periods of time. I always have a problem with these types of solutions of long term acceleration. Once you get to such speeds that make Interplantary travel viable, arent you also going to be at a speed where even the impact of dust particles could devastate your ship. Your ability to maneuver is also compromised with such a solution. Yes. Impact with debris is a problem. Maneuvering less so. But, as I mentioned, going slow isn't safe either... Still the area between earth and mars is mostly empty. It seems to be less of a problem than in earth orbit. For dust to sand size particles segmented shielding should do the job.. Anything bigger... Big enough and you can see it and maneuver around it.. If you are unlucky and hit something the size of a pebble let alone rock.. Big trouble. Don't know the exact odds but I believe your chances of getting there are still pretty good. (I mean by not getting hit.) -- Using M2, Opera's revolutionary e-mail client: http://www.opera.com/m2/ |
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"John Thingstad" wrote in message news On Sat, 13 Nov 2004 02:20:38 GMT, Christian Ramos wrote: Well utilizing the heat from the reactor directly is certainly easier. It was the first idea and explored already back in the 50's. Of course then it was though to be used in the atmosphere something we would never consider today. But a atomic reactor can generate electricity with good efficiency. (Except the RORSAT reactor (Russian..) mentioned elsewhere) Heating has directly you could not possibly put as much energy into the gas. WhileVasimr puts much more energy into the propellant, I'm interested in doing the numbers, since you'll lose energy in the conversion to electricity and back again to heating in Vasimr. Would you assume such a beast would utilise a rankine or stirling cycle for electricity generation? Then there is the fact that the gas flow would have to be high to have a cooling effect. Not necessarily. If the the reactor also serves the function of electricity generation you would likely have an independant cooling system given the propulsion system will not be constantly in use. Although balancing that could be tricky. P = m*v and we want m as small as possible and v as large as possible. (I am talking about the propellant not the ship per se though the same applies here.) Seems to me magnetic induction of ions wins hands down. I think you need to take into account the conversion losses. Thermal energy available in the reactor to heat propellant versus amount of thermal energy available to input to Vasimr after losses. Also, given our limited understanding of plasma and magentic sciences, are we even sure that such a device would work well in "Outer Space" with all kinds of external plasma and magnetic interactions This later is a question I've never seen addressed so perhaps I'm being paranoid. Knowledge of magnetic's is (or really electro-magnetics) is decidedly where our science is the most advanced. Plasma flow seems sufficiently well understood to make a working motor. It may be advanced from a relative perspective, but still along way to go. Sure you can produce a working motor, I've can produce a working launcher from a softdrink+bottle, but we are talking about it's viability as a propulsion solution. If you also add in the immature technologies it utilises such as superconductors etc, well... (Not that you should be asking me about this.. http://www.ae.utexas.edu/design/phoenix/vasimr.html and references should give you an idea.) Yep. I'm familiar with the engine from tech papers. Again, it still seems a high tech toy looking for a solution. Some references that may be of interest to you, The Development of the VASIMR Engine -International Conference on Electromagnetics 1999 Rapid Mars Transits With Exhaust-Modulated Plasma Propulsion - NASA TP 3539 Accuracy Improvement in Magnetic Field Modeling for an Axisymmetric Electromagnet - NASA/TP—2000–210194 I see it used for manned interplanetary flight. Particularly continous acceleration means that the peaple are exposed to cosmic radiation and zero g for much lesser periods of time. I always have a problem with these types of solutions of long term acceleration. Once you get to such speeds that make Interplantary travel viable, arent you also going to be at a speed where even the impact of dust particles could devastate your ship. Your ability to maneuver is also compromised with such a solution. Yes. Impact with debris is a problem. Maneuvering less so. A problem inplies a solution. I dont think we are anywhere near such a solution, so I would call it a unaddressable problem currently. But, as I mentioned, going slow isn't safe either... Still the area between earth and mars is mostly empty. My comment was directed at interplanetary, in the case on intraplanetary such long acceleration methodolgies could be useful. Although, I have a suspicion that its more useful for unmanned activities in which case you probably would want to use something with less failure points. It seems to be less of a problem than in earth orbit. For dust to sand size particles segmented shielding should do the job.. At the speeds needed for interplanetary travel, segmented shielding simply means a bigger bang when it hits, the energy in such particles at those speeds wont be mitigated by whipple shields with current materials. Anything bigger... Big enough and you can see it and maneuver around it.. At those speeds and with such low acceleration forces, I suspect you would be toast before the computer could even analyze the situation, but we are getting too heavy into hypotheticals I think. |
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